The habitat diversity and structure may be major factors influencing the distribution pattern of mistletoes, common aerial-stem hemiparasites that frequently depend on frugivores for seed dispersal and their host plants for water and nutrients. However, very few studies have linked seed dispersal and seedling establishment for understanding mistletoe plant distribution and plant demography together in different anthropogenic disturbance forest types at a local scale, viewing the seed dispersal process as a continuous loop.
Prof. ZHANG Ling and her students of Xishuangbanna Tropical Botanical Garden (XTBG) chose the generalist mistletoe Dendrophthoe pentandra (Loranthaceae) in Xishuangbanna as a study system. They aimed to investigate how changes in host compatibility, seed disperser behavior, post-seed dispersal processes and forest structure influenced the distribution of mistletoes. They first asked whether the distribution patterns of D. pentandra differed in plantations and tropical forests. They then asked whether host characteristics (host abundance, diameter at breast, height and crown diameter) affected the infection pattern of D. pentandra. They finally addressed the question how different seed dispersal and post-seed dispersal processes influenced host infection of D. pentandra across different forest types at the local scale.
To determine the distribution of D. pentandra, four 1-ha blocks (each 100 m × 100 m) 100–300 m apart were selected in XTBG. They observed mistletoe D. pentandra infection patterns at the scale of individual trees and sixteen 400-m2 forest plots in adjacent plantation and rainforest within Xishuangbanna. To elucidate what determined infection patterns at different scales and in different forest types, they observed the behavior of major avian seed dispersers and carried out a seed inoculation experiment to examine how post-dispersal compatibility and light incidence affected the infection of different hosts.
The study found that mistletoes aggregated more within trees in a plantation, with infection prevalence and number of host species infected by mistletoes significantly higher in the plantation than in the forest at tree and plot scale, despite there being many more species and tree individuals in the forest. Two seed dispersers provided different initial distribution templates, thus influencing spatial patterns at the tree and plot scales. However, additional elements such as post-dispersal and abiotic factors may also be important in different forest communities affecting the survival of D. pentandra seedlings during the mistletoe’s early life.
The study entitled “Host compatibility interacts with seed dispersal to determine small-scale distribution of a mistletoe in Xishuangbanna, Southwest China” has been published online in Journal of Plant Ecology.
Key Words
mistletoe, aerial-stem hemiparasites, tropical, plantation, forest, seed dispersal, distribution, host compatibility, Xishuangbanna
Contact
Prof. ZHANG Ling Ph.D
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
Tel: 86 691 8715948
Fax: 86 691 8715070
E-mail: zhangl@xtbg.org.cn